It is necessary to supply heat to a hydrogen supply device for producing hydrogen rich gas in a system where a medium for chemically repeating the storage and release of hydrogen is mounted; a hydrogen supply device is provided for producing hydrogen rich gas from the medium; and the hydrogen rich gas produced in the hydrogen supply device is supplied to an internal combustion engine. The system becomes highly effective when waste heat from the engine is utilized for the heat to produce hydrogen rich gas since new energy is not needed to supply to the hydrogen supply device. However, a system for managing the waste engine heat supplied to the hydrogen supply device is necessary because an amount of the waste engine heat changes depending on the driving point of the engine.
As a conventional system for managing heat and power, JP-A-2000-303836, for instance, describes a system where an engine, a reformer and a fuel cell are included and manages heat by switching a heat supply method between during start-up and after warm-up. It also describes a system which combines systems for managing the heat and for managing power utilizing the load-efficiency characteristics of the engine and the fuel cell.
A system described in JP-A-2000-303836 is a hybrid system, power sources of which are an engine using a medium as a fuel and a fuel cell to generate electricity using fuel gas containing hydrogen reformed from a medium in the reformer and oxygen gas. Since the fuel supplied to the engine is the medium in this hybrid system, it is difficult to suppress CO2 emissions. On the other hand, in a system where hydrogen rich gas produced in the hydrogen supply device is supplied to the engine, it is possible to suppress CO2 emissions and to make the system environmentally superior. However, in the system where hydrogen rich gas produced in the hydrogen supply device is supplied to the engine, it is necessary to manage both the waste heat and the efficiency of the engine because the fuel to be supplied to the engine is reformed from the medium by using the waste heat of the engine. Moreover, in order to make the whole system highly efficient, the system needs to manage a driving point of the engine to be in a region of high thermal efficiency, combining a motor, an energy storage device and an engine.
An object of the present invention is, in an engine system including a medium which chemically repeats the storage and release of hydrogen, to provide an engine system where CO2 emissions can be suppressed and system efficiency is excellent.